U.S. patent number 4,284,126 [Application Number 06/055,043] was granted by the patent office on 1981-08-18 for environmental control system for a multiple room structure.
Invention is credited to N. Rick Dawson.
United States Patent |
4,284,126 |
Dawson |
August 18, 1981 |
Environmental control system for a multiple room structure
Abstract
The environmental control system of the present invention is
used in a multiple room structure which includes independently
actuatable heating and cooling devices in each room. This system
operates by monitoring the ambient air temperature in each room and
by controlling the operation of each heating and cooling device to
achieve a desired ambient air temperature in each room. The
structure of the present invention includes a room status indicator
which indicates the occupied or vacant status of each room. A
centrally located control panel permits an operator to assign
heating mode and cooling mode temperature limits to each room. A
temperature sensing and control unit is positioned in each room and
is coupled to the heating and cooling device in each room. The
temperature sensing and control unit measures the ambient room air
temperature, determines the operating mode of the heating and
cooling device and controls the operating mode of the heating and
cooling device in response to a control signal. A central processor
is coupled to the room status indicator, to the control panel and
to each of the temperature sensing and control units to
continuously monitor and control the operation of each room heating
and cooling device to achieve the desired ambient room air
temperature in each room.
Inventors: |
Dawson; N. Rick (Daytona Beach,
FL) |
Family
ID: |
21995195 |
Appl.
No.: |
06/055,043 |
Filed: |
July 5, 1979 |
Current U.S.
Class: |
165/11.1; 236/1B;
236/51; 340/4.3; 340/501 |
Current CPC
Class: |
G05D
23/24 (20130101); G05D 23/1917 (20130101) |
Current International
Class: |
G05D
23/24 (20060101); G05D 23/20 (20060101); F24F
003/00 (); G05D 023/19 () |
Field of
Search: |
;165/11,12,22 ;62/126
;236/1R,1C,1B,46R,47,51,94 ;340/147R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Davis; Albert W.
Assistant Examiner: Focarino; Margaret A.
Attorney, Agent or Firm: Duckworth, Hobby, Allen, Dyer &
Pettis
Claims
I claim:
1. An environmental control system for a multiple room structure
having an independently actuatable heating and cooling device in
each of said rooms, said system operating by monitoring the ambient
air temperature in each of said rooms and controlling the operation
of each of said heating and cooling devices to achieve a desired
ambient air temperature in each of said rooms, said system
comprising:
a. a room status indicator for indicating the occupied or vacant
status of each of said rooms;
b. a control unit for permitting an operator to assign heating mode
and cooling mode temperature limits to each of said rooms;
c. a temperature sensing and control unit positioned in each of
said rooms and coupled to said heating and cooling device in each
of said rooms for measuring the ambient room air temperature and
determining the operating mode of said heating and cooling device,
and for controlling the operating mode of said heating and cooling
device in response to a control signal, said temperature sensing
and control unit including first temperature measurement means for
measuring the ambient air temperature in said room and second
temperature measurement means for measuring the temperature of the
conditioned air discharged from said heating and cooling device;
and
d. processor means coupled to said room status indicator, to said
control unit and to each of said temperature sensing and control
units for determining the desired ambient room air temperature for
each room and for transmitting an appropriate control signal to
each of said temperature sensing and control units to continuously
control each of said heating and cooling devices to achieve the
desired ambient room air temperature in each of said rooms.
2. The system of claim 1 wherein a single electrically conductive
path couples each of said temperature sensing and control units to
said processor means.
3. The system of claim 2 wherein said electrically conductive path
includes a twin conductor wire.
4. The system of claim 1 wherein the heating and cooling device in
each of said rooms includes an intake port for receiving ambient
air from said room and an exhaust port for discharging conditioned
air into said room.
5. The system of claim 4 wherein said first temperature measurement
means is positioned in said intake port of said heating and cooling
device and wherein said second temperature measurement means is
positioned in the exhaust port of said heating and cooling
device.
6. The system of claim 1 wherein said first and second temperature
measurement means include first and second thermistors.
7. The system of claim 6 wherein each of said temperature sensing
and control means is coupled to said processor means by a single
twin conductor wire.
8. The system of claim 7 wherein said first thermistor is coupled
in series with a first diode oriented in a first direction and with
said twin conductor wire and wherein said second thermistor is
coupled in series with a second diode oriented in a second
direction and with said twin conductor wire.
9. The system of claim 8 wherein said processor means includes
means for alternately transmitting an electrical signal current in
first and second directions through selected ones of said twin
conductor wires to alternately measure the resistance of said first
and second thermistors in selected temperature sensing and control
means.
10. The system of claim 9 wherein said electrical signal
transmitting means transmits direct current in first and second
directions through selected ones of said twin conductor wires.
11. The system of claim 9 wherein said electrical signal
transmitting means transmits a D.C. voltage in first and second
directions through selected ones of said twin conductor wires.
12. The system of claim 1 wherein each of said temperature sensing
and control units includes control means for selectively operating
said room heating and cooling device in response to the control
signal generated by said processor means.
13. The system of claim 12 wherein said control means includes
switch means for selectively connecting and disconnecting a source
of electrical power from said room heating and cooling device.
14. The system of claim 1 wherein said processor means
includes:
a. a process controller for controlling the operation of said
system; and
b. switching means coupled to said process controller and to each
of said temperature sensing and control units for selectively
addressing a predetermined temperature sensing and control unit
designated by said process controller.
15. The system of claim 14 wherein said processor means further
includes room temperature measurement means coupled to said process
controller and to said switching means for transmitting an
electrical signal through said switching means to said temperature
sensing and control unit addressed by said switching means to
alternately measure the ambient room air temperature in said
designated room and the temperature of the conditioned air in said
designated room.
16. The system of claim 15 wherein said room temperature
measurement means includes voltage measurement means.
17. The system of claim 1 wherein said processor means is a digital
computer.
18. The system of claim 1 wherein said room heating and cooling
device includes a thermostat and wherein said processor means
continuously controls each of said heating and cooling devices to
prevent operation of said heating and cooling devices beyond a
predetermined ambient room air temperature limit.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to environmental control systems, and
more particularity, to environmental control systems for multiple
room structures having independently actuatable heating and cooling
devices in each room.
2. Description of the Prior Art
The prior art discloses a wide variety of devices intended for use
in multiple room structures such as hotels and motels and which
reduce the heating or cooling load in unoccupied guest rooms. This
reduction in heating and cooling load is accomplished by permitting
the room temperature in unoccupied rooms to rise above the comfort
level when the environmental control system is in the cooling mode
and by permitting the temperature in unoccupied rooms to decrease
below the comfort level when the environmental control system is in
the heating mode.
U.S. Pat. No. 4,060,123 (Hoffman) discloses a device of the type
described above which overrides the room heating and cooling unit
thermostat to cause the room temperature to increase or decrease to
an energy saving temperature when the room occupant removes the
room key from the room control unit.
U.S. Pat. No. 4,021,615 (James) discloses an energy conservation
system which enables a room clerk to transmit an audio tone over
the telephone lines into each vacant guest room to turn off the
room heating and cooling device. This system also permits a room
clerk to turn on a room heating and cooling device just before the
room is to be occupied. The James system is a passive system in
that no information is transmitted from the room to the central
control unit.
U.S. Pat. No. 3,934,797 (Perlmutter) discloses a temperature
control system which incorporates a pair of thermostatically
controlled switches within each room of a multi-room structure. One
thermostat permits a first predetermined temperature to be
maintained if a room is occupied while the second thermostat
permits the room temperature to be maintained at a second level
when the room is unoccupied. A clock controls the selection of one
of the two thermostats and thus designates when the "occupied"
thermostat will be actuated and when the "unoccupied" thermostat
will be actuated.
U.S. Pat. No. 3,964,676 (Rooks) discloses an electronic morning
start-up control for a building temperature control system. A
cyclic clock starts a fixed period auxillary timer a predetermined
time before building occupancy is to commence to permit the
building temperature to be raised or lowered to a predetermined
level by the time occupancy commences.
U.S. Pat. No. 3,945,564 (Smallegan) discloses a temperature control
system which provides an automatic reduction in room temperature
during night time hours.
U.S. Pat. No. 4,031,322 discloses a telephone operated signalling
system which utilizes the twin conductor telephone wires which
extend between the front desk of a motel or hotel and each
individual room. This system permits maids and other employees to
transmit signals to the front desk during clean up activities.
Other related inventions are disclosed in the following U.S. Pat.
Nos.: 3,908,899 (Millard); 3,743,009 (Dagerford) and 3,933,197
(Zimmer et al).
SUMMARY OF THE INVENTION
The present invention contemplates an environmental control system
for a multiple room structure having an independently actuatable
heating and cooling device in each room. This system operates by
monitoring the ambient air temperature in each room and by
controlling the operation of each room heating and cooling device
to achieve a desired ambient air temperature in each room.
The inventive system comprises a room status indicator which
indicates the occupied or vacant status of each room. A control
unit permits an operator to assign heating mode and cooling mode
temperature limits to each room. A temperature sensing and control
unit is positioned in each room and is coupled to the heating and
cooling device in each room. This unit measures the room air
temperature and permits a determination to be made as to the
operating mode of the heating and cooling device. This unit
additionally controls the operating mode of the heating and cooling
device in response to a control signal. Processor means is coupled
to the room status indicator, to the control panel and to each of
the temperature sensing and control units in order to determine the
desired ambient room air temperature for each room and to transmit
an appropriate control signal to each temperature sensing and
control unit. The environmental control system of the present
invention is thus able to continuously control each of the room
heating and cooling devices to achieve the desired ambient room air
temperature in each room.
DESCRIPTION OF THE DRAWINGS
The invention is pointed out with particularity in the appended
claims. However, other objects and advantages together with the
operation of the invention may be better understood by reference to
the following detailed description taken in connection with the
following illustrations wherein:
FIG. 1 is a generalized block diagram of the various elements of
the preferred embodiment of the present invention.
FIG. 2 is a detailed block diagram of a part of the preferred
embodiment of the present invention.
FIG. 3 is a detailed block diagram of the remaining elements of the
preferred embodiment of the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
In order to better illustrate the advantages of the invention and
its contributions to the art, a preferred hardware embodiment of
the invention will now be described in some detail. FIG. 1 is a
general level block diagram of the system of the present invention
while FIGS. 2 and 3 illustrate the specific structure which
comprises the environmental control system of the present
invention.
Processor means 10 is the primary active element of the
environmental control system and includes process controller 12,
room temperature measurement means 14, switching means 16 and
control signal generator 18. Each room in the multiple room
structure controlled by the environmental control system of the
present invention includes a room heating and cooling device 20 and
a temperature sensing and control unit 22. The temperature sensing
and control unit 22 measure the ambient room air temperature,
assists in determining the operating mode of the heating and
cooling device and controls the operation of heating and cooling
device 20 in response to a control signal. A two conductor wire 24
couples switching means 16 of processor means 10 to the temperature
sensing and control unit 22 which is positioned within each
separate room of the structure.
Room status indicator 26 is coupled to process controller 12 and
indicates to process controller 12 the occupied or vacant status of
each room controlled by the system. Control panel 28 permits an
operator to control and modify the operation of the system and to
determine the preset temperature limits assigned to any particular
room. Control panel 28 also displays other data and permits other
types of inputs to the system which will be discussed below.
Referring now to FIG. 2, the specific structure utilized in the
preferred embodiment of the invention will be discussed in some
detail. The following discussion will assume that the environmental
control system of the present invention is installed in a
multi-unit motel or hotel and that control panel 28 is positioned
at the check-in desk. Control panel 28 will normally include a lock
out device which prevents non-supervisory personnel from
substantially modifying the operation of the system. Supervisory
personnel will be issued a key or equivalent device which will
disable the lock out device and permit full control over the system
through the keyboard of control panel 28.
The operator of control panel 28 initially depresses the "R" key
and then depresses a sequence of digital keys representative of the
room number which he wishes to modify or evaluate. In FIG. 2, the
operation of the heating and cooling device in room 234 is to be
modified or evaluated. Once the room number has been identified,
process controller 12 will transmit a sequence of data to control
panel 28 which will be displayed on the remaining LED displays
immediately below the room number read out.
LED display 30 indicates that room number 234 has been assigned to
zone 3. If the operator wishes to assign room 234 to a different
zone, he must depress key "Z" and then the numeral key
corresponding to the desired zone number. Each room can in this
manner be independently assigned to different heating and cooling
zones which have various temperature limits as is discussed below.
Corner rooms, rooms having a northern exposure, rooms exposed to
the prevailing wind, rooms receiving the afternoon sun, or rooms on
the interior of the building can each be independently assigned to
a different zone which will maximize the effectiveness of the
operation of the heating and cooling system controlled by the
environmental control system of the present invention.
The next level of the LED display designated by reference numerals
32 and 34 indicates the peak heating temperature and the minimum
cooling temperature of an occupied room in zone 3. Similarly, LED
displays 36 and 38 indicate the maximum heating limit and minimum
cooling limit for a vacant room in zone 3. If the operator wishes
to reprogram any of these limits he depresses either the "O" or "V"
keys and appropriate numeral keys on control panel 28 which enables
the reprogramming of the occupied and vacant temperature limits
displayed on LED displays 32, 34, 36 and 38.
The heating and cooling temperature limits discussed above cause
the room temperature in a room in zone 3 to be maintained at a
temperature no higher than 72 degrees when the environmental
control system is in the heating mode and the room is occupied and
at a temperature no higher than 57 degrees when the system is in
the heating mode and the room is unoccupied. In a corresponding
manner, when the system is in a cooling mode, a room in zone 3 is
cooled to a temperature no lower than a temperature of 78 degrees
when it is occupied and to a temperature no lower than 95 degrees
when the room is vacant. The numbers shown on control panel 28 of
FIG. 2 are representative only, can be readily modified as
described above and are independently controllable for each zone to
which a particular room is assigned.
LED display 40 indicates the check-in delay time in hours. The
check-in delay temporarily modifies the heating and cooling
temperature limits in an occupied room at the rate of 2.degree. F.
per hour for a predetermined designated time immediately following
the time when a guest checks into the room. The numeral "4"
displayed on display 40 indicates that a check-in delay of four
hours has been assigned to all rooms in zone 3. During the initial
portion of this four hour check-in delay, the occupied heating
limit is raised eight degrees to 80 degrees and the occupied
cooling limit is lowered eight degrees to 70 degrees. These
modified limits are reduced one degree per half hour and at the end
of four hours will have been brought to the normal limit indicated
on the display panel. This initial eight degree temperature limit
modification permits the room temperature to stabilize during the
heating or cooling period initially following check in, prevents
erratic operation of the system and obtains comfortable
temperatures in the room in a minimum period of time. The "C" key
permits reprogramming of the check in delay time and therefore the
magnitude of the initial temperature limit change.
LED display 42 displays a number representative of the desired
percentage reduction in peak power demand by the environmental
control system. Since power companies charge commercial customers
partially on the basis of peak electrical load, substantial
economies can be realized for a commercial user if the peak demand
can be reduced. In a hotel having 100 separate rooms, it would
normally be possible for as many as 100 of the room heating and
cooling devices to be operating simultaneously. If this occurred
once during the period of a single month, the surcharge charged by
the utility company for this peak demand would significantly affect
the electrical bill for the hotel. The system of the present
invention by actively limiting the maximum number of room heating
and cooling devices which can operate at any one time can
substantially limit the peak demand.
Led display 42 displays a number which corresponds to the
percentage demand saving which is desired. A desired savings of 25%
will indicate to process controller 12 that no more than 75 of the
hotel's 100 room heating and cooling devices must be permitted to
operate at any one time. This objective is achieved by sequentially
shutting down the room heating and cooling devices in selected
rooms for a period of time such as five minutes each when the
ambient outside temperature is either extremely high or extremely
low and more than 75 percent of the system heating and cooling
devices would otherwise be activated. After the five minute shut
down interval which is applied to any selected room has expired,
the device resumes normal operation until a device in each room has
been cycled off for five minutes. Thus for a one hundred room
system, only seventy five of the room heating and cooling devices
are permitted to operate at any one time. In the preferred
embodiment of the present invention, the "fan only" mode of
operation of the room heating and cooling device is not affected by
the demand limit function described above.
Only as many rooms as necessary to satisfy the required demand
reduction are shut off as described above. If, at any given time,
20 rooms, for instance, were not operating for any reason. Then, in
the example above, only 5 additional rooms would need to be shut
off. Rooms counted as not operating would include both those shut
off in the room by controls inherent in heating and cooling device
20 and those shut off by the present invention because of excessive
ambient air temperature.
The "E" key eliminates a selected room from system control and
permits the room heating and cooling device to be directly
controlled by the guest. When the guest checks out and the selected
room assumes the "vacant" status, the normal temperature limits are
reapplied to that particular room. The "E" key is the only
programming key which can be operated by non-supervisory personnel
such as a room clerk. A room clerk is able to actuate the displays
of control panel 28 but is not otherwise able to reprogram the data
displayed.
The occupied or vacant status of each room can be communicated to
process controller 12 by a management computer if the hotel has
such a device which maintains an updated room status condition. In
the preferred embodiment of the present invention, a separate
status indicator panel is provided and includes a single pole
double throw switch 44 which is assigned to each room and actuated
by the room clerk. One position of this switch corresponds to a
vacant status. A plus or a minus eight volt electrical signal is
transmitted by a conductor to N-position analog switch array 46. In
the position indicated in FIG. 2, a plus eight volt signal will be
coupled through switch array 46 to conductor 48 which transmits
this signal to data interface 50 of process controller 12. When
processor controller 12 reads the plus eight volt signal
corresponding to the selected room, the occupied or vacant status
of the selected room is readily determined. The plus eight volt
signal from switch 44 will not actually be connected to electrical
conductor 48 until the control bus transmits an appropriate control
signal to the control input of switch array 46.
The ambient room air temperature and operating mode of heating and
cooling device 20 in each room is determined with the assistance of
the electrical components shown in the block designated by
reference number 52 in FIG. 2. This circuitry represents a portion
of temperature sensing and control unit 22 illustrated in FIG.
1.
Semiconductor diode 54 and thermistor 56 are coupled as shown
across two conductor cable 58. Similarly, semiconductor diode 60
and thermistor 62 are coupled across cable 58 with a reverse
polarity as illustrated. Thermistor 56 is placed in the conditioned
air output duct of heating and cooling device 20 while thermistor
62 is placed in the input or return air duct of heating and cooling
device 20. The resistance of thermistor 56 is thus inversely
related to the temperature of the ouput air of heating and cooling
device 20 while the resistance of thermistor 62 is inversely
related to the ambient room air temperature.
To measure the output air temperature of heating and cooling device
20, the control bus of process controller 12 actuates analog switch
64 to couple positive constant current source 66 to conductor 68
which is coupled to the input of N position analog switch array 70.
The address bus coupled to process controller 12 selects the switch
within analog switch array 70 which corresponds to the particular
room being evaluated by the system. When an appropriate signal is
transmitted from the control bus to switch array 70, the addressed
switch is closed and the current impressed on conductor 68 is
coupled to conductor 58. A predetermined known current flow is thus
established from positive constant current source 66 through diode
54 and thermistor 56. The approximately 2500 to ten thousand ohm
resistance of thermistor 56 predominates over the other resistances
such as the resistance of conductor 58 and generates a voltage
which is amplified by non-inverting voltage amplifier 72. The
control bus actuates analog switches 74 and 76 to momentarily
couple the amplified voltage output from amplifier 72 to capacitor
78. The foregoing electrical components constitute a sample and
hold circuit. The voltage on capacitor 78 is coupled to one input
of voltage comparator 80. The output of voltage comparator 80 is
coupled through a comparator interface 82 to process controller 12.
The output of digital to analog interface 84 is coupled to the
input of digital to analog converter 86. The output of this digital
to analog converter is coupled to the second input of voltage
comparator 80. Process controller 12 controls the operation of
digital analog converter 86 through the feedback path established
through voltage comparator 80 to reach a successive approximation
measurement of the voltage existing on capacitor 78. In this manner
the voltage generated by the current flow through thermistor 56 is
accurately measured. After the initial circuit calibration and
since the resistance of thermistor 56 is the only circuit variable,
the voltage measured by process controller 12 corresponds to the
temperature of the output air from room heating and cooling device
20.
To measure the room ambient air temperature, analog switch 64 is
actuated by the control bus to couple negative constant current
source 84 through analog switch array 70 to conductor 58. As a
result of the polarity of diode 60, current is permitted to flow
only through thermistor 62. The voltage generated by this constant
current flow is amplified by inverting voltage amplifier 86 and the
magnitude of this voltage is measured in a manner identical to that
described previously in connection with the voltage output of
non-inverting voltage amplifier 72.
By alternately measuring the voltages produced by the temperature
variable resistances of thermistors 56 and 62, process controller
12 is able to determine the ambient room air temperature in a
selected room designated by its address bus and is also able to
determine whether the output air flow from the room heating and
cooling device 20 is greater than or less than ambient room
temperature. An output air temperature from heating and cooling
device 20 significantly higher than the ambient room temperature
corresponds to the system heating mode while an output air
temperature significantly lower than the ambient room air
temperature corresponds to the system cooling mode. If the ambient
room air temperature and the output air flow temperature are
substantially the same, either an "off" condition or the "fan only"
condition is indicated in which the heating and cooling device
blower motor is operating but the unit is neither heating nor
cooling.
When process controller 12 determines that the desired temperature
limit has been exceeded in the room which it is currently
addressing, process controller 12 transmits an output signal
through data interface conductor 88 which sets a digital latch
assigned to the addressed room in N-bit digital latch 90. This high
binary output on the addressed digital latch is coupled to a
control input of a corresponding analog switch in analog switch
array 92 causing it to assume a closed position. A 5 KHz audio
frequency generator 18 is coupled to a common switch terminal of
each switch element within analog switch array 92. The closure of
the single pole single throw switch in analog switch array 92 which
corresponds to the room addressed by process controller 12 couples
the 5 KHz audio frequency signal from control signal generator 18
through conductor 58 to temperature sensing and control unit 22.
This 5 KHz A.C. signal passes through capacitor 94 and illuminates
LED 96. LED 96 is optically coupled to control circuitry which will
be described below and causes the room heating and cooling device
to which it is coupled to be de-energized. Process controller 12
controls the timing of switching means 16 so that current generated
by current sources 66 and 84 is not present on conductor 58
simultaneously with the 5 KHz audio frequency signal generated by
control signal generator 18.
Process controller 12 generates control bus signals which cause the
system to first measure the resistance of thermistor 56, next to
measure the resistance of thermistor 62, and determine, from
memory, the occupied or vacant condition of the room, and, finally,
determine if that room has exceeded the appropriate limit. Before
this process is begun, process controller 12 first inputs the
occupied or vacant condition of each room as previously described,
and stores such condition in memory. The sequence just described is
then repeated for each room. Finally, the appropriate control
signals are transmitted to each room.
Referring now to FIG. 3, that portion of the circuitry of
temperature sensing and control unit 22 which actually energizes
and de-energizes heating and cooling device will be described.
Power supply 98 is connected by plug 100 to a source of A.C. line
voltage and converts this A.C. line voltage into a lower voltage
D.C. output to a 24 V.A.C. control voltage. A phototransistor 102
is coupled to the D.C. output of power supply 98 and is optically
coupled to the output of LED 96. When LED 96 is energized,
phototransistor 102 is turned on. The output from the emitter of
phototransistor 102 is amplified by amplifier 104 and the output
signal from amplifier 104 switches on triac 106. Triac 106 and a
thermal delay relay 108 are coupled across the A.C. output of power
supply 98. Thermal delay relay 108 includes a set of normally
closed contacts which are actuated from the normally closed to the
open position approximately 30 seconds after the A.C. voltage is
applied to the heating element of thermal delay relay 108 by the
actuation of triac 106. The thermal delay relay 108 controls the
operation of heating and cooling device 20 by applying and removing
A.C. line voltage from output plug 110 as illustrated.
Process controller 12 controls the operation of temperature and
sensing in control unit 22 so that LED 96 is never turned off for a
period of less than two minutes. As a result of the thirty second
thermal delay, heating and cooling device 20 will thus always be
energized for a minimum 11/2 minute time period and will cool or
heat for this minimum period of time. Process controller 12 will
not begin sensing temperatures in a room until the heating and
cooling device has been operating for the minimum time interval.
Since temperature readings are taken only from rooms in which LED
96 has been in the off condition for more than two minutes, the
circuitry of the present invention will never sample the 5 KHz tone
since it is utilized solely to turn off or de-energize heating and
cooling device 20.
An abbreviated operational sequence for a single room occurs in the
following steps.
1. Address a specific room.
2. Output the latch in latch array 90 low to permit heating and
cooling device 20 to operate.
3. Delay two minutes to allow the time delay relay 109 to be
de-energized and for conditions to stabilize.
4. Address analog switch array 70 to the appropriate room.
5. Apply positive constant current.
6. Wait for voltage to stabilize.
7. Sample voltage on line conductor 48.
8. Measure voltage using successive approximation method.
9. Convert voltage to an outflow air temperature measurement.
10. Apply negative constant current.
11. Permit voltage to stablize.
12. Sample voltage on line conductor 58.
13. Measure voltage by successive approximation method.
14. Convert voltage measurement to ambient room air
temperature.
15. Determine operating mode of heating and cooling device 20
(heat/cool/fan only) by comparing measured temperatures.
16. Determine occupied or vacant status from memory.
17. Determine zone assignment from memory.
18. Determine appropriate temperature limit for designated zone
from memory.
19. Compare measured room ambient air temperature to indicated
temperature limit.
20. If appropriate, output appropriate latch in latch array 90 to
activate LED 96 to turn off heating and cooling device 20.
21. If this sequence did not result in turning off the heating and
cooling device 20, then repeat steps 4 through 20. If this sequence
did result in turning off heating and cooling device 20, then wait
10 minutes if room is occupied, or wait 120 minutes if room is
vacant, and repeat steps 1 through 20.
The specific electronic structure of electronic circuit elements
such as process controller 12 has not been disclosed in precise
detail since these details are well known to those skilled in the
art. In the preferred embodiment, A Motorola MC6802 microprocessor
constitutes the central processing unit and scratch pad random
access memory. Additional random access memories and read only
memories are incorporated within the system and the selection and
connection of these elements is well known to those skilled in the
art. Sufficient disclosure has been recited above to enable a
computer programmer of ordinary skill in the art to readily draft a
program corresponding to the process steps described above.
Motorola MC14051B devices are used for analog switch array 46 and
70; Motorola MC14066B devices are used for analog switch array 92;
and Motorola MC14099B devices are used for digital latch array
90.
In many installations the heating and cooling device located in
each room may also include a thermostat which formerly controlled
the operation of the device in both the heating and cooling modes.
When the present invention is coupled to a unit of this type, the
system of the present invention and the heating and cooling device
thermostat effectively operate in series so that when the
environmental control system is in the cooling mode, the heating
and cooling device thermostat will permit a room occupant to select
a temperature on the thermostat higher than a centrally assigned
room temperature limit. For example, if an occupied room has a
cooling mode temperature limit of seventy-eight degress, the room
occupant may set his room thermostat to a temperature of eighty
degrees and maintan the eighty degree temperature or any other
temperature which is higher than the cooling mode temperature limit
of seventy-eight degrees. Similarly, when the environmental control
system is in the heating mode, the heating and cooling device
thermostat may be set to permit a room occupant to maintain a lower
temperature than the heating mode temperature limit designated by
the centrally located control panel.
In another embodiment of the present invention for use in a
multi-unit apartment complex or in a multi-room office building,
the room status indicator may be deleted from the system since the
occupied or unoccupied status of each apartment or each office will
not change on a frequent basis. In this embodiment, different
temperature limits may be assigned to vacant apartments or
unoccupied office space by merely assigning those areas to a zone
having the desired temperature limits. Thus the room status
indicator element is not required for these particular uses.
It will be apparent to those skilled in the art that the disclosed
environmental control system may be modified in numerous ways and
may assume many embodiments other than the preferred form
specifically set out and described above. For example, far more
sophisticated signalling systems could be incorporated for
transmitting signals over line conductor 58 between processor means
10 and temperature sensing and control unit 22. Thus numerous
additional control functions could be accomplished with only
minimal modifications of the circuitry of the preferred embodiment.
Room status indicator panel 26 may not be necessary if the
particular user already possesses a management computer system
which maintains current room status data. In this embodiment, an
appropriate output of the management computer would be coupled
directly to process control 12 and would thereby indicate the
present room status at all times. Control panel 28 might also be
modified to include an additional read out which would indicate to
a room clerk the present temperature in each room. The operating
sequence of the environmental control system of the present
invention could be modified in many different ways while still
remaining within the scope of the invention. Accordingly, it is
intended by the appended claims to cover all such modifications
which fall within the true spirit and scope of the invention.
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